Large aperture four-member photographic objective



SEARCH ROOT F- KU PKA March 6, 1951 LARGE APERTURE FOUR-MEMBER PHOTOGRAPHIC OBJECTIVE Filed July 20, 1943 Fig. 1

D r I d 6 SEARCH Root Patented Mar. 6, 1951 UNITED STATES PATENT OFFICE LARGE APERTURE FOUR-MEMBER PHOTOGRAPHIC OBJECTIVE Frantisek Kupka, Prague, Czechoslovakia, as-

signor to Meopta, spojene zavody pro jemnou mechaniku a optiku, narodni podnik, Prerov, Czechoslovakia Application July 20, 1948, Serial No. 39,732 In' Czechoslovakia August 4, 1947 1 Claim. (Cl. 88-57) 1 2 My invention relates to an objective for photothrough ds, and the axial air separat o s between graphic and similar purposes, wherein in addia mpon 1 through tion to astigmatism and coma particularly aper- The following tables give numerical values in ture and color defects are corrected and which millimeters for three embodiments of the invencomprises four air separated components of which 6 tion, all hav a focal length f=100 a d the first is a simple convergent element, the secn ap u e ratio of 3 2 -67 and 1 rend a. compound convergent meniscus consisting spectively. These tables contain also the refracof a convergent element cemented in front of a tiVe indiees throu for the D Sodium divergent element, the third a simple divergent line a d the respective Abbe numbers through element and the fourth a simple convergent elef the glass d in each of the fi p c ment. elements.

The object of my invention is to provide an m p 1 mpr v ph r p objective of the type (16- [Focal length=l00 mm. Aperture ratio, 1115.

scribed above and particularly applicable to cinematographic purposes. The new objective has a high luminosity and maybe more easily 22 333138 '5} ni fi ti i l l manufactured than known ob ectlves of the same :3: gz g-go 2mm:-

type as it employs spherical surfaces of small 2; j 111 321161216 2: 1

curvature. In order to accomplish the ob ects yf-fg gg gig-i of my invention I impart to my new improved rZ=+1o9I0o b4= I objective the following characteristics: the ce- 42-82 mented surface of the compound convergent memscus forming the second component of the Example 2 objective has a radius of curvature of an absolute value between six times the equivalent of 25 [Fwanengthflmmm' Aperture focal length of the objective and infinity; the surface of the first component facing said second r +so.o d1= 9. 15 nm=l.6598l n=5o.a component has a radius of curvature of a value fljj figg 3: 3: g8 gig-f, between two and a half times the equivalent of r4=6l6.0- dl= 2.60 n v=1. 71715 Wv=296 the focal length of the objective and infinity; the 53125;? SE $1 $8 mean refractive index of the material used for +s1.e bs= 9.45 the convergent element of said second component 3: {3:}? is greater than 1.65; and the Abbe number of the material used for the divergent element of said second component is at least thirty percent Example 3 smaller than the Abbe number of the material [Focal length=l00 mm. Aperture ratio 1:13.] used for the said convergent element of said second component.

The said and other objects of my invention and g igIg gkigfg nggiigggs i v3 the application of 1ts principles willbe more fully g 13 3: 7 2; 6 2332 71715 g g zg understood from the following specification when r5=+191.3 b1= 8.6 npv=l.6l2l6 w=5s.0 read with the accompanying'drawing in which 3:33;; 5 one embodiment is illustrated. n= +91. 8 b4=15. 4 In the drawing Fig. 1 shows a sectional view through a lens system embodying my invention,

and Fig. 2 shows a diagram of the spherical and he d1agram shown in F1g. 2 is based upon the chromatical correction curves of the aperture defollowlng Values ind cating the spherical and feet for the spectral lines 0, D Rand at a focal chromatical corrections for the embodiment according to Example 1:

length f=l00 mm. 5

The objective illustrated in Fig. 1 is composed of four air separated components I, II, III and IV h 0 D of which the first is a simple convergent element, the second a compound convergent mems- +0120 0 0 cus consisting of a convergent element cemented 19.45 -o.2 9 -o.a 7 -0. 2s -o.523 in front of a divergent element, the third a simgigg 1g: fig 181%,}; T 8: gg I3:

ple divergent element and the fourth a simple convergent element. The radii of curvature of the individual surfaces are indicated 11 through 1'9, In the foregoing table h represents the height the axial thickness of the individual elements (1.1 above the optical axis of the system at which a particular ray strikes the object side of the first convergent element cemented in front of a diverlens. The values outlined in the table for the gent element, the third a. simple divergent elelines C, D, F and G, which are the Frauenhofer ment, and the fourth a simple convergent elel n 0f h p c m. are Obtained y deducting 'ment, and wherein the cemented surface of said the chordal distance for a height h=0 in 1ine--- e ond component ha a radiu of curvature of D from the chordal distance for the respective absolute value between six times the equivalent height h and the respective line. of focal length Of the objective and infinity; the

The following table Shows the sewers surface of the first component facing the second eflicients for each surface 1'1 through '9 and for component has a radius of curvature of a value the sodium line D, namely the coeflicients A of 10 between two and one half times the equivalent spheri al a erra B of coma, I of as i m focal length of the objective andinfinity; the tism, P of field curvature. and E] of distortion. mean refractive index of the material used for Th total 8111118 in each column indicate the the convergent element of the second component sulting values f the Whole Optical y is greater than 1.65; and the Abbe number of the material used for the divergent element of r A B F El the second component is at least thirty percent smaller than the Abbe number 01' the material 1 +0. 5007 +0. 3905 +0. 3040 +0. 5096 +0. 6355 used for the convergent element of the same com- 2 as: 18-95%? 133355 i panes. 4 411498 Him -0Ioe2c 0' +01 0152 20 FRANTIsEK KUPKA. 5 "i233 lit??? "3%??2 3 3233 182223 7 -0:5280 -0Im1 -0I9902 413257 -3I1ess REFERENCES CITED 8 -o. 0012 -o.o1ov -o.o9os +0.3483 +2.17ss 9 44.2173 +0. 2295 +0.4s20 +0.5214 +0 1 The following references are of record in the +0.3004 +0.1715 -0.1313 +0.501c +0.00a9 25 file of this patent:

UNITED STATES PATENTS What I claim as my invention and desire to Number Name Date secure by Letters Patent: 1 584,271 Bertele May 11, 1926 A photographic objective with large relative 1708 863 Bertele Am 9 1929 aperture, corrected for spherical and chromatic 3o 2170423 Richter 1939 berrations, coma and astigmatism, and compris- 2297452 Berek et aL Sept. 29 1942 ing four air-separated componentsof which the 2399858 Cox May 1946 first is a single convergent element, the second 2:449:769 Cox Sept 1948 a compound convergent meniscus consisting of a 

